Dispensers for dilute liquid formulated chemical compositions are often designed to spray a stream of water onto a solid mass (e.g., a block or powder) of a concentrated composition for a limited period of time to produce a liquid chemical concentrate. This concentrate is then diluted with an appropriate amount of water to produce a use solution. The dispensers often require the user to manually control the dispensing time for the concentrate and the make-up water, which can result in widely varied use solutions due to operator error, inattentiveness, fluctuations in water pressure and temperature, etc.
Attempts have been made to incorporate timers and switches in an automated dispensing system. These systems typically control the delivery of the liquid concentrate and make-up water, etc., to a receiving vessel to form a use solution. While these devices can be very accurate, they can nonetheless produce potentially dangerous concentrated liquid solutions prior to the addition of the make-up water. Moreover, these devices tend to be relatively complex and expensive. Additional drawbacks of the present dispensers include complicated calculations required to produce varying amounts of the use of solution. Either the operator or the electronic control system of the dispenser must calculate the time or flow of the liquid concentrate and the make-up water to provide the use solution, which may result in excessive effort on the part of the operator or excessive cost for electronic controllers, and may introduce concentration errors in the use solution.
Dispensers incorporating a plurality of adjustable valves to provide a constant proportion of chemical concentrate and make-up water have also been used. These dispensers have a water supply valve as well as individual valves to control the water flow rate to a spray nozzle for formation of the liquid concentrate and the flow rate of the make-up water. While these dispensers allow for variations of use solution concentration, they require adjustment by a skilled operator, and are difficult to maintain at stable concentration levels over their lifetime. Further, the use solution concentrate can be adjusted by unauthorized personnel without quick detection.
The solid chemical dispenser art has made several advances over the years. However, present designs require skilled operator or expensive electronic controls to provide accurate delivery of use solutions. In addition, present systems can provide an initial charge of highly concentrated and potentially dangerous liquid concentrate solutions prior to dilution with make-up water. Present constant ratio systems require careful calibration of valve settings to provide desired concentrations.
Therefore, in view of the deficiencies in prior art dispensing systems, a simple yet versatile dispenser is needed which is capable of providing use solutions at varying controlled concentrations and at any desired volume. More particularly, a dispenser is needed which can provide a use solution wherein the concentrate and make-up water are delivered simultaneously at a constant ratio, and which ratio is simply and accurately altered by an unskilled operator.
Dispensing systems have also been developed which are designed to dispense a plurality of use solutions, whereby different solutions may be selectively dispensed by an operator. For example, for cleaning, different use solutions may be needed for different cleaning tasks, or for following a cleaning schedule or regimen.
However, dispensing solutions for different tasks or regimens requires an operator to select the proper use solutions to be dispensed at the proper times. An operator may forget the place in a particular cleaning schedule, particularly when many operators are relied upon to carry out a particular schedule. Others may simply choose not to follow the schedule. In some instances, deviations can result in less than optimal cleaning results.
Therefore, there is also a need for a dispensing system which can facilitate dispensing of a plurality of use solutions such as cleaning solutions for different tasks and/or for following a preferred schedule. In particular, there is a need for a dispensing system which can control the particular use solutions dispensed by the system for different tasks or schedules, to minimize the possibility of operator error when using the system.